Generally for most of the colleges, there is no entrance exam for getting into BCA. It all depends upon the marks of 12th class. But you should take BCA only if you are capable to self-learn as many new things are coming up in the market which is still not taught in the colleges.

Also you should keep in mind to do BCA from a good college only. The higher your marks in 12th class, the better your chances to be in a good college.

Hope my answer helps you!