I’ve never gotten a ticket for speeding because of a plane (I don’t think) but yes, some states use aircraft to check for speeders. I doubt it’ a full time endeavor due to cost effectiveness though.
In OK I’ve seen the state trooper planes a few times. Usually they stick to the interstates but I have seen one flying low and slow over the 2 lane county road to my home.
Roads are laid out here in 1 mile increments and the guys in the plane put a stopwatch on someone they think is speeding and time them between increments. The math is done and they radio ahead for a ground unit to hopefully catch them.
I believe highways in some states have paint mark increments on them for use by troopers in aircraft.