I don't understand your question about the servo - but

RE: ADC -

The value returned by the ADC will be (Vin/Vref) * ( ( 2^n)-1) Where N = the number of bits of your ADC.

And example: If you are using 5V for Vref and Vin = 1V and you are using a 10 bit ADC, then the count will be 205