Not sure why you can’t connect to the hotspot but there might be a few different reasons so I would suggest checking a few things. As I understand when using the laptop, you see among WiFi connections your iPhone?
If not, go to your iPhone > Settings and make sure that Personal Hotspot is on. If it is not on, switch it on, to do so Mobile data (option above) also need to be switched on.
Once this is switched on, you need to make sure that the iPhone is not far from the laptop and also it is connected to Mobile network (you need to have an active data plan from your mobile phone providers).
If these 3 conditions are met, you should see iPhone connection among Wifi options on your laptop. If you still cannot connect, it is probably the wrong password you are typing on your laptop. Again, go to iPhone > Settings > Personal Hotspot, see the password and make sure you type it correctly. Below a screenshot with these options:
So, to sum this up, to connect to iPhone hotspot you need
1. Switch on the Personal Hotspot and Mobile Data on your iPhone.
2. Switch WiFi on your laptop
3. You should see the iPhone among available Wifi Connections
4. Click on it and enter the correct password
I hope this helps. It is possible to connect to iPhone hotspot via Bluetooth and USB but the method I described is the most common one.