The first sensor I encountered was the scale that weighs bags of laundry at the laundromat.
This light uses some kind of motion detection to turn on when people are walking near it at night.
The T-Mobile store has video surveillance and a motion sensor in the doorway.
I walked past a lot of ATMs, which sense the magnetic strip on a credit card.
I’m not sure if this bell in the hardware store counts as a sensor, but I thought it qualified because it takes an input and gives an output.