I haven't used one personally. But, an old Airstream buddy of mine had a hub meter. I just use a spreadsheet and log my starting and ending mileage for the trailer.
As mentioned above, my F150 tracks the miles. I've pulled this current trailer 5700 miles with just this truck alone, not counting all the miles accumulated behind my Ram.
2017 Jay Feather 7 22BHM Baja/Andersen WD
2018 F150 4x4 3.5L Ecoboost Max Tow
2015 MB Sprinter 2500 Passenger 2.1L Diesel
2007 Ram 2500 4x4 Cummins 5.9L G56