Hi!!
I recently got a magnet for Christmas and as I’ve been fooling around with it I found a cool way to analyze picking technique. I’m not sure if this is exclusively an Apple feature or not but if you have a Mac book and an iPhone you can stream your phone camera to your laptop. I’ve been using the Facetime menu to get a live feed of my picking. The only problem is my recent calls menu cuts off the higher strings. I’ve tried doing this in Photo Booth and it works a little better but there’s still parts of the menu that block it off. I haven’t found any camera apps that are able to zoom out so I can get a full scope so this might be a potential Cracking The Code software product idea. If this already exists comment below!
There are many ways to stream your phone’s screen to the mac. The easiest is a dedicated app you have on macOS called … iPhone Mirroring 
Have you been able to get 120fps on iPhone mirroring?
Haven’t tried but why would you need that if you watch yourself in real time? 120 fps is helpful for slowing down recordings.
That’s what I’ve been using. The problem there’s no dedicated software I can use. Both facetime and photobooth have menus blocking part of the view. I haven’t gotten use to practicing with my magnet yet but it seems easier than having to record, take it off, then fight it to get it back on. Plus I can use the live feed to help me adjust my picking if I’m using the resources on here
https://obsproject.com/kb/mac-installation
You can even capture your frontal view with the mac camera at the same time.