I carry around a small notebook (usually a 48 page Field Notes) for short fleeting notes. Later I copy them into my commonplace book/zettelkasten/digital garden and expand upon them.
Waste books were used in the tradition of the commonplace book. A well known example is Isaac Newton’s Waste Book (MS Add. 4004) in which he did much of the development of the calculus. Another example is that of Georg Christoph Lichtenberg, who called his waste books sudelbücher, and which were known to have influenced Leo Tolstoy, Albert Einstein, Andre Breton, Friedrich Nietzsche, and Ludwig Wittgenstein.
Lichtenberg, Georg Christoph (2000). The Waste Books. New York: New York Review of Books Classics. ISBN 978-0940322509.