How can I evade being spied on?

I’m sure my MacBook has been accessed, since I’ve had it for years & it was mysteriously dented a few months ago & recently it mysteriously started making a popping sound when I close it. I also hear the person in question rushing to click away from something every time I enter the room & finally just saw a website I visited recently (from my secondary account with a new password & that I set to delete history when I log out). So it’s definitely compromised.

I’m also sure my iPhone has been accessed, but I update my password on both devices a lot these days, so it must’ve been via Face ID. I installed system updates & am turning Face ID off while I sleep. Is that enough or could it still be compromised? I’m stuck in this situation for now, but how can I collect evidence?