First make sure the latest software for your 3D Mouse is installed (see here).
Then open, for example, the 3Dconnexion Viewer (on Windows: Start – All Apps – 3Dconnexion – 3Dconnexion Viewer) and see if the object is moving even if not touching the device cap.
If the object is moving without touching the 3D Mouse cap, then calibrate the device.
Locate the 3Dconnexion icon in the System tray, (Black and White Icon). Right click and select Calibrate.