Accelerometers and Inertial Motion Sensors (IMUs) detect the 3D orientation and acceleration of the object that they're attached to – for example, a wand, or a glove.
The Equipment Room has the following sensor boards. I believe that all of them have example code for the Arduino. Some of them require that you download one or more libraries. (The tutorials and example code document how to do this.)
Also see Properties of Electronic Components