Smoothing Accelerometer/Gyroscope Displacement Tracking for Mouse Motion
Since we don't get many details of your design (hardware, software, etc), I can only offer a generic answer.

First step is to look at your sensor output.  Can you get a telemetry channel out of your system that you can plot and visualize?  From this you'll be able to determine your static noise versus the meaningful signal that you are trying to detect and respond to.  And when accelerometers are involved, noise will abound!

Once you have this data, you'll be well equipped to design a filter to suit your needs.  Especially with IMUs, it doesn't help to just shotgun it with a filter and call it good.  You need to read your signal in real time and design a filter to fit the need.  If you find that you need Kalman, then fine, but maybe you don't need it.  Or maybe you want it but can't until you've modeled your noise.  

Different filters have different pros and cons, so you have to determine what filtering you can apply and what it will cost you (lag time is usually involved).  With IMUs, don't be surprised if you have to layer some filters as well, and perhaps filter->process->filter->process for a couple iterations until you can clearly detect your meaningful data.