There is no any common entrance exam for BCA program. There are many Universities which offer the program. Each college has different criteria for the admission. If you explain the particular college name then I can help you better.
BCA is undergraduation course amd for taking admission in in this college eligibility required is to pass 10+2 with 50% as aggregate and yes, there is one entrance exam named CET which needa to be given for admission and this is conducted by institute only.
All the best.