What would be the best way to accumulate evidence of police stalking?

I'm acutely aware there's a large pool of mental health sufferers whose lives are afflicted by gangstalking disorders and that's why I'm uninterested in debating and simply would like to know the best possible course of action for absolutely PROVING what they're doing to differentiate my case from the disorder and have the concrete ability to start building a civil rights case against them.

Essentially I was stupid a couple years ago and started flipping off the local state police like a moron and after a couple months of this stupid behavior they started ROUTINELY following me around and constantly drive by my house in fifteen minute intervals.

It's all so painfully obvious and there's ALWAYS a squad car 15, 30,45, and on the hour like clockwork.

It's been a couple years now and I'm honestly just ready for it to be over so I need serious help starting to build a case against these fascist fucks.