Just a few weeks, and I'm not an expert, this is the first device like this that I've bought (digital hygrometer that is). I found it after reading a post here that mentioned the brand - you may find that post if you search this brand, Extech.
They have some with detachable probes. That might be a good option to explore, being able to route a cable with just the plug end rather than the probe end having to go through any holes, or maybe extra probes for additional reading locations.
The probe needs to not take any direct hits of mist/water, or else you'll see 99% humidity until it drys out. When I have it mid cage under a leaf, I see 82-88% peak humidity during mistings.