Hello, I hope you are doing well

Yes. A candidate who is having commerce background is eligible to join BCA course. But all the institutes will not accept these candidates.

Most of the institutes or colleges have the following common eligibility criteria to give admission for BCA course:

• Candidate should have completed 10+2.
• The percentage of marks in 10+2 will be minimum of 50%.
• The candidate should have Mathematics as one of the subject in 10+2.

As you are from commerce background, you might not be having Mathematics in your 10+2.So you won't face a big problem at all.

Do any computer certification course. Some colleges will consider this to give admission for BCA course. Some other colleges will conduct entrance exam to give admission for this course.

Collect the list of top colleges offering this course around your location. Know  the eligibility criteria and try to be eligible for it. After the completion of BCA course, try to join MCA course.

Hope this helps