Custom plugin with cordova in ionic app

Any one know how to add custom plugin with ngcordova ?

I could get the existing plugin details, for ex, device information.

Now I have created my own custom plugin and installed via plugman. But not sure how to access inside ionic

Just look at the implementation for the various existing plugins and follow that logic. You can find examples here:

One of the most basic implementations would be this one:

It really is nothing more than a AngularJS Q promise wrapper to your implemented function(s)