Is it permissible to use things that are no longer beneficial in the workplace for personal purposes, as compensation for overtime and personal expenses incurred for work?

You are not permitted to use these things except with the permission of the authorized entity. Overtime cannot be claimed unless the contract stipulates compensation for it and the company has not paid it, provided it does not exceed your due. As for the money you spend for work, if it is necessary to safeguard what is under your responsibility, then you have the right to claim it and obtain it if the company does not pay it. However, if it is not necessary, you do not have the right to seek reimbursement from the company unless the contract stipulates it or the company approves it.