The Russians used a Pencil.
Urban Legend. Pencils are not used in orbit because the graphite lead can break off, float off, and since graphite is conductive, cause a short in electrical circuits. That and they can burn in a 100% oxygen environment. After the Apollo 1 accident, objects of that type were forbidden.
Someone else spent over a million developing a zero-g pen, but they sold them to NASA for just $3 apiece.