Yes, you can format cells in Microsoft Excel to display measurements in millimeters. Here's how:

1. Select the cells that you want to format.
2. Right-click on the selected cells and choose "Format Cells" from the context menu.
3. In the "Format Cells" dialog box, click on the "Number" tab.
4. In the "Category" list, select "Custom."
5. In the "Type" field, enter the following format code: 0.00" mm"
6. Click "OK" to apply the formatting.

Now, any values entered into the selected cells will be displayed in millimeters with the "mm" unit of measurement. For example, if you enter "25" into a formatted cell, it will be displayed as "25.00 mm".