It's called Figurine Notation and there are chess fonts out there that you could use in place of letters.
Having said that I must suggest you don't use that notation. These days everyone understands algebraic notation. Not many people want to learn the older notations. Three of the most used notations have been algebraic, descriptive, and figurine. Of those three notations figurine is probably the least used and is the one I most dislike.
Thank you to Gomer_Pyle and dmc286 for your positive responses.
My motive for wanting to use figurine notation is that I'm hoping to produce a book of games and I will need an appropriate font. I'm told that Unicode is the way to go but some (many?) systems may not be able to recognise the figurine notation.
I wouldn't dream of using the descriptive notation! I'm old but not that ancient!
I would like to display the moves of a chess game in a form suitable for publication. The common practice is to replace the initial letter of a piece by a little picture of the piece. For example, the first game in the link below is between Zukertort and Steinitz. Under the diagram are the moves of the game but notice how White's third move is recorded: it is not Nc3 but a picture of a knight, followed by c3.
How can I do this?
https://www.chessgames.com/perl/chessgame?gid=1132661