In your menu bar, near the right, you now see
that you have two active keyboard layouts:
one is your primary keyboard layout (in this case
‘ABC’, a Latin-script keyboard associated
with the English language),
and the other is Unicode Hex Input,
which you can now select and use.

Note also that you now have access to two new items:
‘Show Emoji & Symbols’, a bit of a misnomer since it
in fact gives you access to all of Unicode;
and ‘Show Keyboard Viewer’, which is self-explanatory.