Author here - I added an addendum to the end of the article. I write notes in a notes app (I use notion, but you can use whatever). Then I usually text it to her (though email would work fine). I keep it very simple, and I type a lot faster than I write by hand.
Are we talking about a post-it note? Are the notes in a physical notebook? Is this done via some sort of mobile app? On a WhatsApp message, perhaps?
I know it will be different for everyone, probably, but I think it is important to know one that is already working for someone.