Some small voltmeters can be modified to read down to 0 volt by cutting a link and providing the meter first with the voltage needed to drive the meter, and then another lead to measure the voltage in question. The link is usually in the area of a couple of voltage divider resistors on the input.
With this arrangement it uses a common negative.
Edit...I did one just the other day to read 0-1v but sadly could not use it as I required a floating input.
Do you have a link to your particular meter?