Re: Looks like a good tool...
If you have a device close enough to the laptop to sense this low level MEMS leakage, then skip a step and simply have your own microphone to pick up the same sound the laptop's microphone is picking up!
This thing is really a massively brute force solution to figuring out if your microphone is enabled. Anyone worried enough that they'd buy this device should physically cut the wires to their laptop's microphone and camera, and get a USB attached webcam they can connect only when they want to use it.
I mean a physical switch is great, but what if doesn't work as advertised? Can you really trust it does what it is supposed to and any failure will fail in the 'off' position? Those who are suitably paranoid would say no, I'm sure.