Hygrometer that plugs into outlet?

A little background (sorry if long). Some folks in my neighborhood have had issues with moisture in their crawl space. My uncle has an HVAC business and helped me mount a 3 speed fan under there and put a hinge on the crawl space door. When it warms up, I open my crawl space vents and the crawl space door (I put a screen over the hole to keep critters out)

The fan is on a smart outlet so I can control it from an app but it’s not on a timer or anything.

I got one of those cheap outdoor thermometers that measures moisture. Hung the sensor under the middle of the house and check the humidity sensor to know when to turn my fan on. The downside is that whenever the batteries die, I have to get under there and replace them.

My question is does anyone know if they make those same thermometers that plug into an outlet? I’m not ready to go the dehu and encapsulation route, as I don’t currently have a moisture problem. Just slight condensation on some of the duct work. Just trying to be proactive. Fan does a good job of circulating air down there and keeps the humidity at a reasonable level.

Would a hygrometer intended for a dehu (where you set it to kick on at a certain humidity) work with a regular fan?

TIA