Install charmap.app by entering the following commands in the terminal:
sudo apt update sudo apt install charmap.app
Character map for GNUstep
This is a character map. It is developed using the GNUstep development environment (www.gnustep.org) and is meant to contribute to GNUstep's promise towards a desktop environment. . Charmap offers font selection, allowing one to easily see all the glyphs which a particular font offers.