Read the accelerometer Sensor with precision.
This example allocates memory:
void Update()
{
    //Get Precise Accelerometer values 
    Vector3 accelValue = preciseAccelValue();
    Debug.Log("PRECISE X: " + accelValue.x + "  Y: " + accelValue.y + "  Z: " + accelValue.z);
}
Vector3 preciseAccelValue()
{
    Vector3 accelResult = Vector3.zero;
    foreach (AccelerationEvent tempAccelEvent in Input.accelerationEvents)
    {
        accelResult = accelResult + (tempAccelEvent.acceleration * tempAccelEvent.deltaTime);
    }
    return accelResult;
}
This example does not allocates memory:
void Update()
{
    //Get Precise Accelerometer values 
    Vector3 accelValue = preciseAccelValue();
    Debug.Log("PRECISE X: " + accelValue.x + "  Y: " + accelValue.y + "  Z: " + accelValue.z);
}
Vector3 preciseAccelValue()
{
    Vector3 accelResult = Vector3.zero;
    for (int i = 0; i < Input.accelerationEventCount; ++i)
    {
        AccelerationEvent tempAccelEvent = Input.GetAccelerationEvent(i);
        accelResult = accelResult + (tempAccelEvent.acceleration * tempAccelEvent.deltaTime);
    }
    return accelResult;
}
Note that this is not filtered. Please look here for how to smooth accelerometer values to remove noise.