I use that digital acurite one linked above for an ambient temp thermometer on the warm side, I like how it gives the minimum and max temp so I can make sure that side doesnt get too warm in the ambient (since my heat lamp hits that side more) .... and of course it also has the humidity on it
However, I ALSO use a separate digital therm on just the hot spot under the substrate to monitor the surface above the UTH that does have a probe .... so in effect I have two thermometers monitoring my warm side
And then another one monitoring the cold side with the probes suction cupped a couple inches above the surface (humidity and temp both)
I might be a little thermometer happy lol.....
I have an IR gun too