How unity works with native Mobile applications?

Hi, I am working on a native mobile application.I have one functionality in my app deals with a lot of animations.Its a dynamic character movement according to inputs.In my thoughts, unity might be better option to do this.but none of the other features in my app needs unity .those are easy to do with native functionalities of iOS and Android and hard to do with unity.Can anyone suggest how can I implement unity in my app just for one functionality? do unity has some plugin that works with native applications. Any help will be appreciated! Thanks, Anu