Is a student's salary considered unlawful (haram) because he changed his answer in an exam due to a supervisor's (muraqib's) alert, which affected his outstanding performance?

A man's salary is permissible (halal) if his job is lawful and he performs his work as required, even if there was cheating in his academic exams, because cheating does not prohibit earning from work with those certificates.

Sheikh Ibn Uthaymeen issued a fatwa permitting a student to write down an answer he heard unintentionally, because he did not intentionally commit a sin.

Therefore, this man must ignore these whisperings (waswas) and pay no attention to them, because indulging them leads to evil and tribulation, and turning away from them is the best remedy for them.