Back when we had analog meters like your picture, the power company could install a remote Watt-Hour counter for those homeowners who had a dog in the back yard. They modified the rotating disc inside the meter so that it tripped an electrical contact once per revolution. Each pulse advanced a remote counter, mounted on the front of the house, so the meter reader could read the meter without going the back yard. Once a year or so, they made an appointment to go into the back yard to confirm the main meter reading against the remote counter. Now a days, we have RFID remote reading meters that the power company can read from the street.
If you can get inside the meter, how about using an opto-interrupter to detect the rotation of the disc. I think there are already holes in the disc. This would give you one or more logic-level pulses per revolution of the disc, which you can accumulate in a u-controller. The gearing of the disc to the pointers on the meter face is absolute, and usually printed on the meter face.