There are many different ways to capture external audio for video. I'm highlighting 3 different devices that can be used.
Affiliate links:
Zoom H4N - http://amzn.to/2B3kr5F
Canon 80D - http://amzn.to/2my8pfq
Canon N - http://amzn.to/2D5AcLo
Shot with:
Canon 80D/Canon N
Sound recorded with:
Zoom H4N
iPhone 5c
ZTE Android
In camera
Edited in:
FCPX