Acceleration sensor: Pasco PS-3223 at Conatex Lernsysteme
There are also operating instructions under the links. The sensor can be used on its own, or it can transmit data directly to an Android tablet via Bluetooth live. Here you can download the free App SPARKvue and here the video: Youtube
Only carry out this experiment if you know what you are doing. In particular, you should define a safety zone for the flight of the rocket in which nobody should be present to ensure that nobody is injured by the flying rocket. These instructions should supplement, not replace, your own assessment of the risks and your measures to avert them.
Acceleration measurement with a water rocket: Youtube
Other possibilities would be to attach the sensor to the shoe, for example, and jump. And then just put it in your pocket. Or, or…