Yes, definitely! The only criterion for the Common Admission Test or CAT is that you should be a graduate, and since you have completed your Bachelor of Commerce or BCom, then you are fully eligible to appear for the same. However, it is a totally different matter that when you dive deep into it, you will find that they have other requirements like marks in graduation, Xth, XIIth and so on.

Hope I have answered your question. All the best!