Unknown Humidity Metering Equipment

Commercial Residential Inspection.
HVAC consists of: Several Baseboards under windows. Radiant heating. Bathrooms. Electrically Heated floors. 1-18,000 Heat pump mini split. 1-12000 AC mini split.

Private areas/condo units need to exchange air. I forget the cubic feet per hour rate. The electric duct heater in a chase-way is where I ran across a device next to the THERMOLEC open coil electric duct heater that I suspect measures/sniffs temperature or humidity in the chase-way. Image beow.
Any help would be greatly appreciated. The device is in a white plastic shell about 3" inches square and one inch deep with a dial on top, missing dial. A 1/4" metal hollow probe that extends out the bottom body of the device roughly >< 8" inches. There is a round brown telecommunications cable attached to the side of the device that runs down to an unknow destination.