On your computer,
Start ARDUINO-Genuino IDE
Install the joystick library by Matthew Heironimus, and
SparkFun’s Pro Micro, ATmega32U4, micro-controller Arduino driver.
A) GitHub SparkFun Arduino boards source, B) SparkFun Pro Micro page
Load one of the software Sketches downloaded from my page.
Under Tools: setup Board, Processor, and Port.
Configure any software Option by right-click
and select ‘Comment/Uncomment’ #define compiler directive.
Verify/Compile
Upload when compile is clean

If upload is sucessful, you can now test your new controller.
^{You may want to upload blink Sketch to confirm communications is working between your computer and Arduino.}

To test your new controller within windows:
Start,
Control Panel,
in Search Type joy,
under Devices and Printers Click ‘Set up USB game controllers’,
Click Properties

A button press will light, indicating button activity.
If button does not respond, confirm button wiring and port. Remember within the code, button activity is active low, due to Arduino MCU hardware pull-up resistor. Low is On, High is Off.
When changing assigned button Port/Digital bit, corresponding pull-up resistor must be correctly set.
If pull-up resistor is set, Port/Digital bit will configure for button Input.

Mouse pointer movement will confirm Spinner/Trackball activity;
if there’s no movement, validate +ve/-ve power connections along with both A/B connections.
Quadrature line output require working A/B signal pulses to convey direction and movement (each axis has a pair of signals assigned to either X or Y axes).
To change movement feel, select a different #define compiler directive within the code.