Apogee and Sennheiser have teamed up to produce high-quality lapel mics with lightning connectors, meaning they plug right into "modern" iPhones, iPads, and iPod Touch devices. The two companies announced this partnership in 2015 and brought the ClipMic to market in May of 2015. If you would like to find out all the details or buy one yourself, check it out at B&H Photo/Video/Audio here.
You can use the ClipMic on any iPhone, iPad, and iPod touch that uses a lightning connector. So basically anything since the iPhone 5 or iPad 4th generation and iPod touch 5th generation).
You can't easily attach just any lavalier/lapel microphone to iOS devices. You normally need some sort of adapter in order to make that work. But with the ClipMic, you just plug it into your device and record MUCH better quality audio.
This allows you to record from several feet away from the mobile device and still have professional sounding audio. Without the mic connection, you can still record yourself on video from several feet away. But the audio quality will be pretty bad. Getting a mic up close to your mouth is the first and best way to immediately improve audio quality. But without a way to connect to your iPhone or iPad, this is usually very difficult. The ClipMic fixes that.
I mentioned the high quality hardware. You can read more about that, and about more details in this article about the project - http://www.audiomediainternational.com/new-gear/sennheiser-and-apogee-collaborate-on-clip-on-mics/04359