Download a barcode font (Code 39 and Code 128 are the most common). Install the font on your Windows or Mac system. Open Excel and type your data (e.g., "12345") into a cell.
Use the =IMAGE("URL_HERE") function (in newer versions of Excel/Google Sheets). download barcode to excel
This creates a dynamic barcode that updates whenever the value in cell A2 changes. Download a barcode font (Code 39 and Code