Digital Pin won't ground when set to LOW
Never directly connect a motor to an Arduino IO pin
You will destroy the Arduino.
An Arduino cannot source (or sink in your case) enough current to drive a motor, and if the motor did manage to turn the huge amounts of EMI it generates would literally blast holes in the silicon inside the chip.
You must use a motor driver of some form. If you only want one direction that driver can be a single NPN Bipolar transistor or N-channel MOSFET.  If you need it to change direction then an H-bridge is what you want.