Input.GetAccelerationEvent  

// Calculates weighted sum of acceleration measurements which occurred during the last frame
// Might be handy if you want to get more precise measurements
function Update () {
    var acceleration:Vector3 = Vector3.zero;
    for (var i = 0; i < Input.accelerationEventCount; ++i) {
        var accEvent:AccelerationEvent = Input.GetAccelerationEvent(i);
        acceleration += accEvent.acceleration * accEvent.deltaTime;
    }
    print (acceleration);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Update() {
        Vector3 acceleration = Vector3.zero;
        int i = 0;
        while (i < Input.accelerationEventCount) {
            AccelerationEvent accEvent = Input.GetAccelerationEvent(i);
            acceleration += accEvent.acceleration * accEvent.deltaTime;
            ++i;
        }
        print(acceleration);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Update():
        acceleration as Vector3 = Vector3.zero
        i as int = 0
        while i < Input.accelerationEventCount:
            accEvent as AccelerationEvent = Input.GetAccelerationEvent(i)
            acceleration += (accEvent.acceleration * accEvent.deltaTime)
            ++i
        print(acceleration)