arduino sensor through voltage/resistance drop?

I couldn't quite think exactly what it was called but i was wondering if there is a sensor that could trigger from a voltage drop or just through making a connection? I'm trying to figure out how to trigger a older organ key from the 2 wires coming from it. I have my arduino setup using a piezo to trigger a note when i press on it, but should it be fine with those wires directly connected in place of the piezo?

The only thing i could think of is i would need a resistor somewhere in between im guessing. I have some experience with electronics but as you can see...not much. Mostly worried of frying my arduino but there is no voltage coming from the keys. If anything i guess it would make a connection.

So the key's a switch?

Ground one side, take the other side to an input pin with INPUT_PULLUP. Pin will then be high normally, and go low when the key is closed.