I just received a pop up message that said "device census is using the webcam" isn't device census a Microsoft background program, and why was it using my webcam. I have disabled the webcam now, but still wanted to see if anyone had any answers.
Windows 10 contains a Telemetry service that reports back to Microsoft on hardware usage/errors etc.
Device Census is part of that Telemetry Framework and the process is only gathering data on your usage of the webcam
If you want restrict this access to your webcam, go to Settings - Privacy - Camera and uncheck the option 'Let apps use my camera hardware'
Or to specifically restrict this process scroll down the "Choose apps that can use my camera' list and uncheck "Feedback' hub', this will limit the data being sent back to MS Community and should free up your Webcam . . .