What is sensor cooking in microwave?

The general meaning of "sensor cooking" usually involves using a microwave compatible temperature probe to cook with. Some microwaves have a thermocouple temperature probe that can be plugged into a jack in the cavity of the oven. This (temperature) sensor can tell the control unit in the microwave when the internal temperature of the food item has reached a preset point. Only the factory sensor should be used with a given oven to avoid problems. There are some generic replacements are available and they will work properly and safely if they are the "correct" ones. Consult a microwave technical expert for advice.