Shift - Control - U - <hex> - space allows entering Unicode symbols.
unicode.org/charts has all of them. Uniview seems to be a searchable index.
The motivating examples for me were Hyphen ‐ (2010), En dash – (2013) and Em
dash — (2014).
An alternative to remembering hex sequences is to use the compose key.
First we need to tell Xfce which key to use as the “compose” key. I used the unused Right command (“Win”) key for example, but there are other options that are shown in Keyboard > Layout settings.
xfconf-query -c keyboard-layout -p /Default/XkbOptions/Compose -t string -ns compose:rwin
Then, we can type compose key followed by “–.” to insert an En dash – like this – or an Em dash by using “—” — neat!