Button that does 2 things

So As of Now I have a button that is connecting to a 12V 2 amp Power supply to a Lock. This is a bypass just in case the game malfunction. However if i use the bypass it will open the lock but my arduino code will still be in in it Loop function rather than finished Game function. My goal is to use have this button bypass the lock and go to the arduino to tell it beat the game.

The button and Arduino are far apart as well

Is this feasible without damaging board?

Yes, to sense 12V at an Arduino input you can just use some fairly high value resistors as a voltage divider to drop the voltage and also limit any excess current that might damage the input pin. Is there a common ground between the Arduino and the lock circuit? Does the button open or close the lock? Please supply a drawing of the lock switch circuit.