A family of Microsoft word processing software products for creating web, email, and print documents.
If you want it to be from the file's name (not folder) you can use a filename field.
Note that it will give the full filename including the docx extension.
If the name is used in the document itself, you can use the StyleRef Field.
If it is put into a Content Control in your document, you can map that CC and put a duplicate in the header. Repeating Data Using Document Property Content Controls and Other Mapped Content Controls