I found some documentation but it looks a bit outdated:http://www.cyberciti.biz/tips/linux-server-predicting-hardware-failure.htmlI see that I can specify a device as input but the documentation does not mention anything specific about that. How should I proceed if (for example) I want to detect if  there is a webcam problem? Also is it a good idea to run mcelog at start with a systemd unit? if yes,  which options should I use? 
correct way to use mcelog on latest versions of Debian
mcelog
By default the mcelog package sets up a daemon which translates MCEs into human-readable form and logs them to the system logs. You can then see them in /var/log/syslog or using journalctl. The daemon is started from an init script, there's no need to add a systemd unit for it.It's unlikely the webcam issues you're seeing would trigger MCEs though, so I doubt this would help you. The device specified as input for mcelog isn't an input device, it's the special device used for communication between the kernel and anything interested in MCEs (mcelog in this case).