Using needle to change sim instead of pin provided with phone

The slot where you had used a needle is meant for a specific size pin having a specific sized flat cylindrical head which you might not had observed as it is a small design. On the other hand a needle is a very sharp thing and has a pointed end. When you used it and pressed it on the slot then due to the force it pierced through the slot and went inside. Fortunately, the SIM cards and external SD card are mounted on the SIM tray in a downward facing manner so the needle did not touch the SIM circuit parts and there was no damage to your SIM card or any other nearby thing. So do not worry about that but in the future use the given pin for opening the SIM tray. If you have misplaced the original pin then you can use a flat head ordinary paper pin also but please ensure that it has no sharp end. In a pack of paper pins, we usually find a few flat end pins also that peope discard but they have this interesting appication.

No need to worry. The design of the tray is made in such a way that even if you use a pin it will not cause any damage to the SIM. But it is always advisable to use the pin given by the manufacturer for placing the SIM in its position. If you carefully observe the SIM card the circuit will be in the middle of the sim and around the circuit there will be some paper portions. Even if the needle touches this portion there will not be any problem with the SIM.
In case you have misplaced the pin given by the manufacturer, it is advisable to use clips that are having flat ends but not sharp ends. You can use a paper clip as it will not have a sharp end.