I take notes on my phone, especially if it's something I'll need on-the-go (like a grocery list). But I also write a lot of physical notes with pen and paper.
Especially for things like a remodeling project on the house - I can scribble out my thought process as I go, small ammendments with measurements or whatever as needed, etc. I prefer writing notes by hand, but there's no one right answer. For me, anyway.