Thank you GarryDoes this help?
Record a voiceover in iMovie on Mac
In iMovie on your Mac, record your own voiceover narration to add to your movie.support.apple.com
I don’t have a microphone, yet I suspectSorry I don't have Imovie or an IPhone or a Mac so can't help. Why didn't you use a wind muffler "deadcat" to reduce /cut out wind noise ? something like the one i use over my microphone Not quite like this but I would have thought they made them for Iphones as well
one little trick might help in the future is have the wind blowing on your back so you are acting as a wind break