On Ubuntu: l-ctrl+l-shift+u, <codepoint>, <enter>

Of course, that sucks, so I've programmed a nearby key to act as l-ctrl+l-shift+u.

Several characters can also be typed with Compose Key.

For characters I use regularly (in my case, generally the elder and younger futharks), I've created a keyboard out of an Elgato StreamDeck XL so I can type any of these runes with a single button press.

The question was

> How do you search for *non-unicode* characters in a pdf document

Eh. That was the original question, but I think the implication of some of subsequent questions can be interpreted in multiple ways.

I don't think that not having a physical key on the keyboard has ever stopped anybody from inputing unicode symbols.