Adding alt text to caption or describe objects in files is new relatively easy using Word and, I, Personally, always feel as if the writer/publisher has gone just a little bit more of the distance in including it in texts and documents. Also, if the subject of your paper or book has any relation to disability, it's really poor form to skip using alt text.
https://www.howtogeek.com/424208/how-to-add-alternative-text-to-an-object-in-microsoft-word/
https://www.howtogeek.com/424208/how-to-add-alternative-text-to-an-object-in-microsoft-word/