Awesome snake, great place to start your ball python addiction. I check the package of you hydrometer and see where the sensor is. And place it appropriately. The probe most likely is just for heat. Ball pythons can and will dig and belly burns are a big concern because ball pythons don't seem to feel the burning pain Untill they are badly burnt and blistered! So be careful and get a rheostat to adjust and fine tune your heat pad. 111 is warm but unregulated I temped one at 140.
good luck and have fun with your new Bp. I give you 2 months max before you'll have another one.