If it's an actionable thing I then categorize and schedule it, but I also have a large 'Maybe' list for unwieldy project ideas (52 items and counting).
For random daily or project notes I use a small shell script (and Dock application, via Automator) that creates a daily file and opens the containing folder in an editor:
touch "~/notes/$(date +%Y%m%d).txt"
$EDITOR ~/notes 1>&2 2>/dev/null &
On my phone I use a very simple but therefore fast and effective open source notes application: https://git.savannah.gnu.org/cgit/diary.git. I never write much there, so I just sometimes manually copy it to my other notes.