No idea what that part is, but I have my doubts it's part of what's doing the count down to stop the probe from working. It's a 3 terminal part so my bet would be a fet or a bjt based on the parts surrounding it in the photo. Although it could in theory be some sort of weird count down ASIC to stop functioning after a set length of time, more or less.
Your wording is very poor as to what it's a part of "circuit is a part of smth like a prob head" a probe head on what, what's the equipment. It's easier to make a bet as to what's causing the shutdown if there's more detail. There's also the possibility that there's a legitimate reason for the probe head to stop after a given time (I'm thinking maybe in a medical device there could be genuine reasons to stop after a given length of operation).