Input.accelerationEvents  

// 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 accEvent : AccelerationEvent in Input.accelerationEvents) {
        acceleration += accEvent.acceleration * accEvent.deltaTime;
    }
    print (acceleration);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Update() {
        Vector3 acceleration = Vector3.zero;
        foreach (AccelerationEvent accEvent in Input.accelerationEvents) {
            acceleration += accEvent.acceleration * accEvent.deltaTime;
        }
        print(acceleration);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Update():
        acceleration as Vector3 = Vector3.zero
        for accEvent as AccelerationEvent in Input.accelerationEvents:
            acceleration += (accEvent.acceleration * accEvent.deltaTime)
        print(acceleration)