[alisonkisk]

Physical camera cover; even if it's a piece of electrical tape.

[ashtonkem]

A lot of detached webcams come with flip down privacy guards.

[ghaff]

I think the newer Logitech ones do; I have an older one. I think my point still stands though. You can make a mistake. Of course if your computer is looking at your bedroom, not much you can do other than be careful about your camera not being on and/or privacy shield down.