At last, Mikrotik released version 7.1b with Wireguard support! YES!
You can upgrade your device now by switching to development branch.
So, create new wireguard interface, keys and set port.
Assign IP address to your new interface
[admin@MikroTik] > /ip address
[admin@MikroTik] /ip/address> add address=10.50.20.1/24 interface=wgvpn
On your mobile phone install Wireguard client and make same steps, assign IP address in same subnet, use public key of your Mikrotik.
Now on Mikrotik create new peer with public key of your phone
[admin@MikroTik] /ip/address> /tool/ping 10.50.20.4 SEQ HOST SIZE TTL TIME STATUS 0 10.50.20.4 56 64 126ms 1 10.50.20.4 56 64 52ms 2 10.50.20.4 56 64 80ms sent=3 received=3 packet-loss=0% min-rtt=52ms avg-rtt=86ms max-rtt=126ms
In absolutely same way you can set up private network on your computer.