Hi,

I hope you are doing well.

Yes BCA students are also eligible for writing UPSC EXAM,  you can also give SSC exam.

For the IAS, IFS & IPS, a candidate must be a citizen of India.

For the IRS and other services, a candidate must be one of the following:
A citizen of India

a person of Indian origin who has migrated from Pakistan, Myanmar, Sri Lanka, Kenya, Uganda, Tanzania, Zambia, Malawi, Zaire, Ethiopia or Vietnam with the intention of permanently settling in India

UPSC ELIGIBILITY

All candidates must have as a minimum one of the following educational qualifications:

A degree from a Central, State or Deemed university
A degree received through correspondence or distance education
A degree from an open university
A qualification recognized by the Government of India as being equivalent to one of the above.

Hope this helps you.