Just to add another point for probe placement, all of my thermostats specifically state not to put the probe where liquid can get between the steel tip and the cable. For wet applications, you purchase a probe specifically for that type of application which is appropriately sealed or purchase a specialized casing for the probe based on manufacturer specs. I’m prone to reading all of the literature that comes with my equipment, so maybe others have not.
All of my thermostats/ thermometers have plastic probes. Herpstat manual recommends inside the terrarium but suggests sandwiching as another option.