This is a cheap on camera shotgun mic that comes pretty well reviewed, I own one of these and it works much better the the on board mic. It can get a nit noisy depending on the camera if you have the gain up to much but gain it back a bit and its great for interviews.
https://www.amazon.com/gp/product/B00E58AA0I/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1