assalamu alaykum. what will be better for me as an officer, if i send an clerk/worker to bring a pen, tea or any instrument for me even I can bring it by myself?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If this is the job of that worker for which he was hired, then there is nothing wrong with sending him to perform those tasks, as long as he is paid for doing that.

However, if this is not his primary job, then it is better for you to fulfill your own needs and not to seek the help of others to achieve them so long that you can do them yourself.

The Prophet advised a group of his Companions not to ask people for anything, and thereafter, one of them would drop a whip from his hand and would not ask anyone to hand it to him. [Muslim]

Allah knows best.