Hii!
The eligibility criteria for applying into DRDO exam states that the candidate must have a bachelor's degree in science or 3 years of diploma degree in disciplines such as allied sciences, technology, engineering, computer science etc.,from a recognised university. It also says that candidates in their final year of degree in any relevant discipline may also apply. So, if you feel you satisfy this criteria, you can apply for the same.
Hope this helps.
Good luck!