As you have not explained what it is that you are trying to do, it is difficult to advise. If you are talking about legacy form fields, the answer is that you could apply a barcode font to the field.
However if you have Word 2013 or later you might find https://www.gmayor.com/insert_barcode_addin.htm useful, or if you have Word 2010 as suggested by your message. then see https://www.gmayor.com/bar_coded_labels.htm
Bar codes can be inserted into rich text content controls.

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Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com