I have this doodad that's been bopping around in junk drawers for years. Marked Mechaless Opto-electronic Systems, property of ELMOS. It beeps randomly and a blue light indicates proximity. If you cover the black circle it beeps faster and faster until it shuts down, and you have to push a button by the batteries to start it again. I connected it to a laptop with the USB cable and it didn't do anything.
I think it might just be a demonstration piece for the sensor.
Is it worth throwing back in the junk drawer (at my new house) and keep telling myself I'm going to make something with it, or is it time to toss it?