on my children's laptops I physically opened the cases and disconnected the webcams and mics.

I started doing this after seeing a news article on schools spying on their students using school provided laptops.
the schools could actually control the cam and see your children in their bedrooms getting undressed etc.

alternatively, some black tape on cam and some crap headphones with the cord cut from the plug and the plug inserted into the mic socket will suffice.

buy your own Web domain and set up a mail server on something like a raspberry pi, and stop feeding Google and the likes your information.

like random stuff on Facebook and add random people from around the world to throw off their profiling etc.