This is a non-contact liquid level detection circuit based on a Q-PROX QT114 IC. Two foil strips are placed around the non-conductive (i.e. glass or plastic) container. The trip point will be at about the top of the lower foil. The output at pin-2 switches from +5v to 0V when the level drops below the trip point. You will need to find a circuit/module/interface that lets your computer detect this logic level change. The pot is used to adjust the IC to the specific foil/container/wire-length dimensions. I've used this circuit to maintain the alcohol level in a 1L lab jar, through a solenoid valve (via a driver transistor) from a gravity fed supply jar. The alcohol was evaporated by air flowing through the jar. I was never able to see the change in level, but the the solenoid would cycle to maintain the level. It's that precise. I can't help with the computer interface, not knowing what program your using. Maybe someone else can help with that part.
Ken