Extra non flight control motor

Hello there.
This is my first topic and for starter I should mention that I have zero experience with Ardupilot.
My friend is willing to make a quadx and she
was successfully able to make it using some tutorials on YouTube probably.
But her project needs an extra motor (not for flying) that has to move.
The motor is a 6v DC motor that will be controlled using the transmitters potentiometer or the other sticks.

So she asked me that question and I don’t know how to actually wire it with Ardupilot because I have no experience with Ardupilot.
In the other hand I already have some experience with Arduino.

I have seen that there is an option for adding extra servos.
So do I need to wire the servo output with a transistor to control that motor ( I am talking like if the output that controls the servo is PWM signal )?
Or is there an option or a setting that will allow us to add an extra motor?
And can we power it through Ardupilot’s 5v instead of an extra power supply?

Ardupilot APM 2.8

flysky fsi6

fs ia6 receiver

That’s unfortunate that she has this obsolete Flight Controller that hasn’t been supported in many years. Not many around to help with such old stuff. But the solution is simple. You need a brushed motor ESC (assuming it is brushed, brushless version otherwise). Connect to an unused output and then mix the pot channel on the radio to control it.