First let me tell you who and what I am as a devotee because that might help you to give my answer.
I am devotee of Shree Ram and Lord Hanuman. I am small devotee, not any major one. But as a devotee I want to increase my level in eyes of my Lord so that I can also get moksha. To achieve this righ now I am doing fasts (Vrata) of Lord Hanuman since few months and I am willing to continue this fasts until my last breath. Means, as long as I am alive, I will keep doing fasts on Tuesday for Lord Hanuman.
As I am devotee of Shree Ram also (Both are so close to my heart), so I am doing Satya Narayan Fast also on every purnima since months. And this fast of Narayan, also willing to continue till end of my life. Never gonna quit... I can't say that I don't have any greed in doing these fasts although I am also human that can go selfish sometimes. But my biggest greed is Moksha. That's why I am doing this.
But here I am only for Lord Hanuman right now. So let's come to real question. I heard that Lord Hanuman blesses their true devotee with some sidhies. He is one of the few Lord who gives sidhi/power to their devotee (not completely clear on that point).As per my knowledge, Mata Kali and Lord Hanuman use to give sidhies to thier devotees. So what I want to know is, how one can get any siddhi from Lord Hanuman? Is there any mantra that can help to pleased Lord Hanuman or any other way through which Lord Hanuman will give blessing to their devotee in form of any siddhi?