The heating device is an overhead ceramic heater. There's not a very good way to put it "on" The heating device.
My probe is inside the tank but I've never had an issue with it being there and I have three separate thermometers in the tank so I'm not worried about my temperature. (I replaced the old one with two digital ones but I kept the old one because it's stuck to the back of the tank and I figured might as well leave it!). My ball also never messes with them. Thank you though!
Ok. The ceramic heater can have the probe under the shield cover of the lamp itself. Having the other probe inside the tank is risky but I understand your points. Be careful though.