A metrology tool is arranged to measure a parameter of a substrate that has been provided with a pattern in a lithographic apparatus. The metrology tool includes a base frame, a substrate table constructed and arranged to hold the substrate, a sensor constructed and arranged to measure a parameter of the substrate, a displacement system configured to displace the substrate table or the sensor with respect to the other in a first direction, a balance mass, and a bearing configured to movably support the first balance mass so as to be substantially free to translate in a direction opposite of the first direction in order to counteract a displacement of the substrate table or sensor in the first direction.