Can iOS display the current audio input device? Is there any way to tell whether an attached external mic is making contact with an iOS device?

I am trying to attach an external microphone (Sennheiser MKE-400) to an iPhone 5. The mic has a 3.5mm jack which fits into the iPhone's headphone port. I know that the port is capable of audio input. However, I also know that there are different formats for 3.5 mm jacks and ports, and that there are adapters available, one of which may be required to make this connection, though I am not sure.

I can make a recording with the mic attached, but from listening to it, it is not clear whether the mic is in use or whether the iPhone is using its own, built-in mic.
You would need an adapter to make that mic work with an iPhone.  Such as this one.