I found this hygrometer at PetSmart it is corded you can place it anywhere in the printer works great. Most of them have the item, If you don't have a petsmart near you it shouldn't be too hard to find on amazon.

First this you need to do is take the sensor apart it has 2 small screws on the bottom. Then put it threw the back of the mount then put it threw the whole in the printer then put the sensor back together mount it any where you want in the printer just make sure nothing is going to hit