Hello,
I had the same problem. I wanted to record with audio quality and post for some friend. So i tested a lot of solution but only one seems to work fini with me.
If you have Iphone or Ipad and a Camera adapter then you are already ready. just follow the Instruction inthis video:
https://www.youtube.com/watch?v=0YtptBkY3fcI had a Iphone and a Ipad, but sadly not the usb adapter.
So i went on a Android because the cable could be delivered really fast (2 days).
I have bought cabel for more than 10 sort and fast 50 eur to find the really one that could pass with my settings.
You have to follow instructions on this video:
https://www.youtube.com/watch?v=DCrFjtNXaeki works for me finally with a jack splitter (mic AND Headphones). It is very important that the two output muss be different.
So you have to plug the mini Jack 3,5 to the rose output (mic) and the most important: Turn the button Volume max to the middle .Otherwise it will be louder and inaudible because the microphone output is not basic adjust.
That was the less expansive methode and the more complicated.
If you have money you can choose a professional Video recorder for that.
The Gopro Hero and the mic adapter (fast the same with the earlier method) or the Zoom 2n, Q4n or Q8n.
I hope i could help