Aadhaar is not mandatory for applying to most government job exams — it is usually one of several accepted ID proofs.
You can generally apply using a voter ID, PAN card, passport, driving licence or other photo IDs listed in the notification.
Some exams use Aadhaar-based verification at the exam centre, but an alternate ID is accepted.
Always read the ‘acceptable ID documents’ section of the official notification for your exam.
Whatever ID you choose, carry the original — a photo of it on your phone is not enough.