Play a sound on your iPhone.

If you think your lost iPhone is nearby, you can play a sound on it to help you find it. Sign in to Find My iPhone and select the device you want. Tap to see your options. Tap Play Sound. If your iPhone is online, the sound plays immediately for two minutes. If it’s offline, the sound plays next time it’s online. More: Find My iPhone overview

by via Apple - Support - Most Recent - iPhone