To use in CircuitPython, simply install the [Adafruit CircuitPython bundle](https://github.com/adafruit/Adafruit_CircuitPython_Bundle).
To use in CPython, `pip3 install adafruit-circuitpython-display-button`.
Read the [docs](http://circuitpython.readthedocs.io/projects/display-button/en/latest/) for info on how to use it.