Currently, I use my iPhone SE on the highest possible quality settings. I then upload footage with audio onto Google Drive, download it on my computer, go to my video editing software, and export the audio as a .wav file.

Next, I bring the audio into Audacity, remove background noise, and go on to amplify, normalize, bass boost, and treble boost it. I export this and replace the old audio with this new one; in the programs I use (Vegas Pro and Movie Studio), this is a matter of degrouping the original audio from the video, deleting the original audio, placing the new audio where it was, and grouping the sound and footage together.

tl;dr - Yes, I use an iPhone for my videos, but I use the highest quality settings and fix up the audio in Audacity.