How To Confirm You've Been Hacked?

Hi all

My intention is to defend my privacy and restore some

peace of mind.

I believe some people in my life have somehow gained access to my email account, desktop

computer, possibly even my smartphone.

I don't know the 1st thing about how to go about detecting the intrusion, confirming it and

then achieving the goal of permanently blocking it and defending against subsequent or future

attempts.

It should be noted that I am resigned to the idea of the US government or foreign governments

or Google or Facebook, etc having access to any and all of my digital activity, that's

relatively acceptable as I have nothing to hide and that's the nature of the digital age...

but what I won't accept and will now fight is the idea of a handful of private citizens in my

personal/professional life with potentially malicious intentions having access to my email

computer & phone.

If there's anyone who can provide some suggestions on how to approach/tackle and ultimately

resolve and move past this ugly situation, I'd greatly appreciate it!