Hii Shivdayal!
Some College do provide an option for candidates outside the College to join certain courses and fields such as NCC. This means you can join NCC in Some other College while studying in Some other college. But, those details are not revealed online or in public. You will have to visit the College and get the details from the office itself. And, it also depends on the number of seats left. If the seats are not full they admit outside Candidates too.
Hope you understand.
Good luck!