Let me explain in brief the difference between the SIM storage and the Phone storage. Later section will contain your solution.
There are two types of storage options for contacts, messages etc.
SIM Storage-The contacts which will be stored in the SIM card of the service provider of your device is called SIM stored contacts.
1)You can have your contacts safely stored and is highly portable. Even if tomorrow your phone crashes(formatting etc.) you will have your contacts with you and don't need to search for as when you place the SIM in another device the contacts from the SIM memory will be displayed easily.
2)Your contacts will be safe and private because most applications have access to only the phone memory but not to the SIM memory so some annoying apps cannot leak your contacts info to other third party's
1)As you know the SIM card has very limited space so it cannot have more number of contacts to be stored.
2)Bigger names cannot be saved as there are restrictions to store a name with a limited set of characters(approximately 6 or 7)
3)If you lost the SIM then you have lost all your contacts irrespective of the storage area where you stored.
4)Cannot personalise the contacts stored in the SIM (adding pictures, date of birth, email id etc.)
5)Double display of contact numbers(if you use what's app like messenger it will display double contacts list 1 with the SIM card and 2 with the what's app contacts list)
Phone storage-The contacts which are stored in the phone's storage area and has a predefined space limit by the Manufacturer are phone storage contacts.
1)As the contacts storage area is more you can store more number of contacts when compared to the SIM card.
2)Personalise add / modify any details to your contacts.(Third party apps can add photos etc. to your contacts display.)
3)No double display of contacts if you are using any messenger because all the details of one contact is displayed under a single name.
4)Apps can check your contacts in phone memory and can update it with all the relevant information.
1)As your contacts are being stored on the phone memory your contacts will not be portable because if tomorrow your phone crashes/ modified /updated then you loose all the contacts because the complete phone memory will be wiped out.
2)You will lose security over your contacts as most applications have access to the phone memory and will eventually leak the data to their server's
Now coming to the answer you can simply combine your Facebook contacts with all the details like photos by
Step 1:-First move all your contacts in phone memory
Step 2-Under the display option disable view contacts from SIM (in order to avoid duplicate from SIM card).
Step 3-Next as you have your contacts on phone you can simply synchronize your contacts with your Facebook mobile application.
Step 4(not necessary but good to follow)-After a complete synchronize restart your device and then you can see the pictures of the user from the relevant app's you use.