Mikrotik Tutorial 31 - Firewall Configuration - Most Effective Methods for Blocking Facebook (2019) shows two methods:
The first is to block the DNS resolutions containing the facebook keyword and,
The second is to reset the TCP sessions to the different Facebook domains using an address list.
For this tutorial, you will need one of the following Mikrotik routers:
Mikrotik RouterBoard RB951Ui-2nD hAP
Mikrotik RB3011UIAS-RM
Mikrotik Routerboard RB2011UiAS-2HnD-IN
Mikrotik RB750Gr2
Mikrotik hEX RB750Gr3
MikroTik RB2011iLS-IN
MikroTik Cloud Router CRS109-8G-1S-2HnD-IN
hAP lite
Hap
hAP ac lite tower
hAP ac
mAP lite
mAP
wAP RB951Ui-2HnD
RB951G-2HnD
RB2011UiAS-2HnD-IN
Mikrotik RB941-2nD-TC