hi,

see jee main exam is a national level exam for engineering admission. there is other state wise engineering entrance test to become a engineer. so it is not compulsory to appear in jee main but if you want to study in nits, iits, iiits, centrally funded institute you have to appear in jee main exam.

since you are interested for cyber security, I  would recommend to select b.tech or engineering stream like computer science, information technology to pursue 4 years b.tech/ B.E course.