Generally this type of system is not available in national level exams, be it JEE Main, NEET, JEE Advanced or any other exam. What happens is that you are required to give your thumb impression or fingerprint at a random time during the exam (when the exam is happening, not before, not after, but during the exam) to confirm your presence.

So, in short, in most of the cases you won't be allowed to do this, but just for safety read the regulations for your exam once.

Hope I have answered your question. All the best!