I use these little Acurite temp / humidity gauges inside the enclosure:
AcuRite 00613 Humidity Monitor with Indoor Thermometer, Digital Hygrometer and Humidity Gauge Indicator https://www.amazon.com/dp/B0013BKDO8/?tag=exoticpetnetw-20
AcuRite 00613 Humidity Monitor with Indoor Thermometer, Digital Hygrometer and Humidity Gauge Indicator https://www.amazon.com/dp/B0013BKDO8/?tag=exoticpetnetw-20