Zulu 2 and some other Lightspeed headsets have an app and will do it via Bluetooth.
I've also used a professional quality handheld audio recorder and a proper mono patch cable with 20dB pad (pictured). (Recording device was a Tascam DR-xx series something or other. They make many. Any good online source for musical instruments and electronics will have them, as do Amazon and others.)
And you can always stuff an earphone, yes a boring old regular earphone like you'd see on any old "transistor" radio, inside a headphone earcup and run that to anything that can record audio. (It'll behave like a microphone.) Some people like that because even under an ANR headset it'll pick up some of the ambient noise of the aircraft.
The mics attached to the video cameras usually pick up too much ambient noise and don't have solid audio from the intercom so that doesn't work too well.
If doing video production, I'd mix the pro audio recorder of just the intercom with a very small amount of the ambient noise from the video camera in post-production editing for the absolute best results.
Sometimes (pre engine start and pre avionics master on) your "ambient noise" mic has to be primary in the mix until you even have intercom audio, unless you like the idea of doing engine start with the avionics master on. I don't.
You sync it all with a visible and audible in all microphones hand clap, just like in the movies. That way you know where to align them all on your editing software.
The ambient noise mics can really help make it seem "better" but only if you keep their level in the mix very low. Hearing engine and wind sounds adds to the quality of the soundtrack, if you're doing video, but too much of it is a turn off for the viewer with loud droning noise.