If you are a writer you always carry a notebook.
You never know what you will see or what great inspired thought will come into your head and will be forgotten by the time you are able to get to pen and paper.
Technology allows alternatives. I can make notes on my phone. But this lacks the immediacy and ease of scribbling a few words in a notebook. You can supplement these words with a small sketch or diagram that only you will understand. You do not need to do great art to remind you of how a scene was set out or the layout of a room. I do not want to carry a huge heavy laptop around with me nor even a tablet and really a phone is too small to write any mre than a few sentances without getting an ache in your thimbs.
So notebooks and pencils or pens in the pocket win every time for me.