State and local government will collect your devices and maybe request the data from your cell carrier or a company like Google if they think they need it, but they aren't equipped to hack into either your device or computer. Most state and local level LEOs aren't strongly technical and 99.9% of the stuff you see on TV crime shows where they "hack the criminal" or "trace the criminal's computer/phone/etc..." is BS, though some of it has a minimum basis in real tech.
The federal agencies are another class and the FBI has used direct "attacks" that are a kind of hacking to collect info about people over the internet, but this isn't a widespread skillset there either. From the cases I've read about these tend to be highly targeted efforts. One that comes to mind was the seizure of a server that distributed child porn. The FBI left it running and installed software that was designed to get the real IP address of any's computer who connected to the server so they could trace location and identify suspects who were trading porn on the site. This sort of thing seems to be relatively rare.... In that case they fawked up though, because the warrant they got signed to authorize the surveillance was from a judge without the authority to authorize warrant surveillance across state lines and they charged a bunch of people from various states and then lost on technicalities when the warrants were challenged. So, ingenious tech deployed to catch people who they then discovered they couldn't prosecute cause their warrants were invalid (this came out because some of the people they prosecuted got the warrants declared invalid in court).
Another case involved the police sticking a simple webcam on a telephone poll across the street from the house of the guy who was the suspect, record for a few weeks, and if the could do that legally without a warrant. Became a question of what was the expectation of privacy and I think the guy lost on appeal, but it took a while to get there. I think the court decided it was a public telephone poll / street so there wasn't an expectation of privacy and no warrant was required.
The real hackers in the government are federal and are in the foreign intelligence surveillance business. A lot of these guys are contractors working for various 3 letter federal agencies and the military. They don't care about 99.999% of us, they are looking for terrorists and spying on foreign governments. These guys are the real wizards and they can do some amazing technical stuff, but they make mistakes too (which is usually how we learn about their exploits).
The fact is, most people who are competent software / technology people are in the private sector cause they will make way more $ there than in law enforcement (unless they can become government contractors). A small % are criminals, but again, they aren't really interested in watching you, unless they can get info they can use to make $. They just want to steal your identity and sell it or may try to extort or blackmail you.
Most of what I read about are cases in court that being challenged or appealed.... and generally it comes down to the validity of a warrant, or the governments use of surveillance to collect data without the appropriate warrant. Turns out the LEOs and the government lawyers fawk up on surveillance quite a bit because of incompetence/arrogance -- they think they can skip getting a warrant for some reason or another and then arrest a guy, charge him, and a sharp lawyer gets him off on technicalities.
Lots of people are willing to share any data they have with about you with law enforcement under the right circumstances. In the case of your phone company or Google/f***book/etc... that can actually be a source of income, cause they can charge the government to cover their costs to provide data.
What LEOs can be good at is social engineering and investigation. They can do a good job putting the pieces together and following the breadcrumbs.