1. install UxPlay
2. Install the required GStreamer plugins gstreamer1.0-libav
3. Run uxplay in a terminal

Command: uxplay
using system MAC address 6c:24:08:e6:3b:8d
Initialized server socket(s)
Accepted IPv4 client on socket 27
Local: 192.168.1.100
Remote: 192.168.1.10
Open connections: 1
Client identified as User-Agent: AirPlay/760.20.1
Accepted IPv4 client on socket 29
Local: 192.168.1.100
Remote: 192.168.1.10
Open connections: 2
raop_rtp_mirror starting mirroring
raop_rtp_mirror tcp socket closed
Connection closed for socket 27
Destroying connection
Open connections: 1
Connection closed for socket 29
Destroying connection
Open connections: 0

4. On the iPhone, open Control Center, Tap the Screen Mirroring icon