magic keyboard

♫𝄡𝄢𝄞𝄆𝄇♯♭♯♩♪♫♬ are available in Unicode. To add unicode characters to a title (or caption), type Control-Command-Spacebar to call up the keyboard dialog (Character Viewer) window. Musical symbols are in two places:

00002600 block: Miscellaneous Symbols [♩ ♪ ♫ ♬ ♭ ♮ ♯ ]

and

0001D100 block: Musical Symbols [𝄀 𝄁 𝄂 𝄃 𝄄 𝄅 𝄆 𝄇 𝄈 𝄐 𝄑 𝄒 𝄛 𝄜 𝄞 𝄡 𝄢 𝄩 𝄫 𝄬 𝄮 𝄽 𝄾 𝄿 𝅗𝅥 𝅘𝅥 𝅘𝅥𝅮 𝅘𝅥𝅯 𝅘𝅥𝅰 𝅘𝅥𝅱 𝅘𝅥𝅲 and others]

You can create a shortcut if you open up the Customize List utility:

And add Musical Symbols (ALL the musical symbols will be displayed at once in the window:

Find the symbol you need and double click it to enter into the text in FCPX. [You can copy/paste the characters above into a document you save for future reference as well — whatever is easier.]

In addition to Fox’s excellent answer, you can use the text expansions in System Preferences->Keyboard->Text and assign the desired words or symbols to conveniently chosen abbreviations- eg type mu and press space to get the word Music.

I have to add a little caveat to my previous suggestion: to use the text expansion, you have to be typing in the Inspector, and not in the little caption window that pops up near the timeline.

Here is an example - I created an expansion for option-B. This normally prints an integral sign ∫,

and I associated with it an ♪:

And here you see it in the Inspector: