First, you need to be clear on what you mean by the "voltage of the higher potential" - all voltage measurements are taken between two points, and the result of the measurement is the difference between the potential at those two points. So when you're talking about the "higher potential", that's higher than what?
In concrete terms... You're going to use a voltmeter to measure the voltage at the battery terminal that we've touched, see if the voltage is different before and after we touch the terminal. Every voltmeter has two leads, and one of them will of course go that battery terminal. Where will the other lead go?