We learned a couple of month's ago that Mark Zuckerberg covers his webcam with black tape (via a NY Times article) .
Then FBI director James Comey made the same recommendation:
"There's some sensible things you should be doing, and that's one of them," Director James Comey said during a conference at the Center for Strategic and International Studies."
The truth is bad actors can easily hack into a laptop equipped with a camera without the user knowing it. Travellers are at an even higher risk because airports and hotels are used by intelligence agencies around the world to collect information (especially when you use a WIFI hotspot without first setting up a VPN - read this article).
Instead of using black tape which could leave residue, I bought a re-usable webcam cover from amazon for $3.