Gist for implementing elevation change when button is pressed.

button_animator_state.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_pressed="true">
        <set>
            <objectAnimator
                android:duration="@android:integer/config_shortAnimTime"
                android:propertyName="translationZ"
                android:valueFrom="3dp"
                android:valueTo="0dp"
                android:valueType="floatType" />
            <objectAnimator
                android:duration="@android:integer/config_shortAnimTime"
                android:propertyName="scaleX"
                android:valueFrom="1"
                android:valueTo="0.9" />
            <objectAnimator
                android:duration="@android:integer/config_shortAnimTime"
                android:propertyName="scaleY"
                android:valueFrom="1"
                android:valueTo="0.9" />
        </set>
    </item>
    <item>
       <set>
           <objectAnimator
               android:duration="@android:integer/config_shortAnimTime"
               android:propertyName="translationZ"
               android:valueFrom="0dp"
               android:valueTo="3dp"
               android:valueType="floatType" />
           <objectAnimator
               android:duration="@android:integer/config_shortAnimTime"
               android:propertyName="scaleX"
               android:valueFrom="0.9"
               android:valueTo="1" />
           <objectAnimator
               android:duration="@android:integer/config_shortAnimTime"
               android:propertyName="scaleY"
               android:valueFrom="0.9"
               android:valueTo="1" />
       </set>
    </item>
</selector>