Song Help Request Ulili E Help on Hammer On/Off?

I am entranced by Mr. Iz's Ulili E. I have the chords, but what does he do to make the C, which is the first chord, have that cool hammer On or Off, hey I am new to this so it may be termed a pull on/off for all I know, but I gotta find out how he does this.
Funny as yesterday I was playing Somewhere Over the Rainbow and one appeared. Spooky, but so cool.
Thanks,
BikeUkeGuy

currently listening to TuneYards Gangsta

Hammer on for Uli'Ülili E

The note you are looking for is to hammer on the first fret of the 2nd string while you are playing the C chord - it makes a C sus 4 for the techincally minded -

Iz uses it a lot

Great version of this song on the Descendants Soundtrack too:

Ülili E (Vocal Duet With David Kamakahi)

Aloha - ballybeg

Is this the same technique he uses on Somewhere over the Rainbow, as I hear a single note then the strum. I have the strum down, oh boy, but I was always wondering about that sneaky note. I will try in a few moment...
Thanks...
BikeUkeGuy