All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Your question is not very clear to us, but if you mean that you are appointed by the government to teach some given subjects but you teach other subjects and then you write on the report other than the reality in order to get the salary from the government, then the answer is as follows:
If the subjects you were appointed to teach are lawful themselves like: teaching Arabic, literature, history and so on, then you are obliged to teach them and you do not deserve your salary otherwise. However, you could add to these subjects any exhortations and admonitions that you feel necessary for the students to learn about their religious matters.
Of course you should teach the lawful subjects which you are obliged to teach and write them in the report, and you are not obliged to write the other activities that you do. You can confine the report to the duties incumbent upon you by your contract with the government. By doing this, you combine the governmental duties to the religious and Da'wah duties.
However, not teaching the students what you agreed upon in the contract with the government to teach them and writing in the report something other than the reality, then this is nothing but cheating, treason and lying without a dire necessity.
Allaah Knows best.