Allah has commanded us to keep our trusts, and He has forbidden us to take people’s wealth or property in unlawful ways.
Allah says (interpretation of the meaning):
“Verily, Allah commands that you should render back the trusts to those, to whom they are due.” [4:58]
It was narrated that Abu Humayd al Sa’idi said: The Messenger of Allah (peace and blessings of Allah be upon him) said: “By Allah, no one of you takes anything unlawfully but he will meet Allah carrying it on the Day of Resurrection. I will certainly recognize some of you who meet Allah carrying a camel that is groaning or a cow that is lowing or a sheep that is bleating.” Then he raised his hand until the whiteness of his armpit could be seen and said: “O Allah, have I conveyed (the message)?” [al-Bukhari, Muslim].
Praise be to Allah Who has enabled you to repent. This is a blessing from Allah to you, for which He deserves to be thanked. So praise Allah and ask Him for more of His bounty and help.
You do not have to disclose to the department what you have done; rather it is sufficient for you to return the things themselves or the equivalent in whatever way you can. If you cannot return them then you can give an equivalent amount in charity.
You should try to find the office from which you took them; if you cannot do that, then it is sufficient – in sha Allah – for you to return them to the department itself.
The Standing Committee was asked about a man who used to work in the armed forces and took a coat without permission. They replied:
You have to return something equivalent to the coat that you took or its value to the section from which you took it. If you cannot, then give the equivalent amount in charity to a poor person.
Fatawa al-Lajnah al-Daimah.
And Allah knows best.