Trying to use an external mic with Osmo Mobile can be complicated since your phone is mounted to the Gimbal. However, if you are using a smaller Smartphone (I use the iPhone SE) there is room between the phone and gimbal motor to plug in a mic and still balance the stabilizer. There may also be some Bluetooth solutions out there that don't need any direct connection, but it seems like those setups can be prone to audio sync and dropout problems. So, I have attached a Rode VideoMic Go to the DJI Osmo Universal Mount accessory and it seems to work pretty well without interfering with the movement of the gimbal. I just mounted the adapter so the cold shoes are facing down and then attach the external mic. To use the VideoMic Go you also need the TRS to TRRS adapter cable (model SC7) to connect to the iPhone. iPhone 7 and up would need to use a different adapter, but doubt there would be room for anything since it is a much larger phone.

Anyway, I have found that smaller smartphones seem to work best with the Osmo Mobile, so if you happen to own one and want to try using an external mic, this is one setup that works. I had to take the picture with my phone, which is why you don't see in the attached example image...

Does the mic pick up any noise from gimbal?

DTK Posted at 2017-5-21 18:04
Does the mic pick up any noise from gimbal?

Not when it is mounted in the downward position. Rode says to use Airplane mode for the least RF interference, but I haven't heard anything from the phone or motors getting through the cable shielding, even when the TRRS connector is pressed against the motor.

I did the same thing, works great!
https://forum.dji.com/thread-63407-1-1.html

bradgonemad Posted at 2017-5-25 17:22
I did the same thing, works great!
https://forum.dji.com/thread-63407-1-1.html

Well, lets update this topic in 2018 --  we all know ... 80 % of any Video is Good Audio -- The Omso 2 sucks as DJI have simply and intentional failed to design any capicity for an exteranl Mic -- Yes this is a critical and fatal DJI design flaw as I too have this same MIc External problem -- We have a Samsung G8 Note which has very poor audio recording in the open with the gain pumping up and the Omso 2 does not have even a plug space to insert the audio cable either into the camera directly or on the Omso it self and we need to URGENTLY plug into the Samsung a Robe mic with a standard 3.5mm socket that simply does not fit with the Omso where the phone holder backs up