The most widely supported music symbols are the seven in Miscellaneous Symbols: ♩ ♪ ♫ ♬ and the accidentals ♭ ♮ ♯. The sharp sign ♯ U+266F is not the number sign # U+0023, and the flat ♭ is not the letter b; use the real characters so that screen readers and search understand them.
Clefs, rests, repeat signs and precise note values are in the Musical Symbols block on Plane 1. They need a font such as Noto Music, and some note values are built from a notehead plus combining stem and flag characters, so they are best copied rather than typed.
Click any symbol to copy it. Names link to the full character page with every encoding.