It can only convert voltage - you have to use the current through a resistor for the measurement. Current through a resistor makes a voltage across the resistor proportional to the current. A small value resistor will not disturb the circuit too much, and a good quality op amp can make the voltage large enough for the ADC to handle.
Ok. So assuming I do that would it would be possible to alternate the input to the ADC depending on whether I want to measure voltage or current. Using a decoder on the input signal for instance??