If I understand correctly, it is 2billion years old, but 50million years ago it merged with another star, making it more massive and thereby more bright an visible from earth. Fun fact: Due to it beeing a yellow supergiant it will turn red in a couple of thousand years and then die quiet soon.

Source: https://www.scientificamerican.com/article/how-old-is-the-north-star-the-answer-could-change-our-maps-of-the-cosmos/