Wireshark Capture time for packet in/out of eth

I ran wireshark to listen to two network interfaces eth0 and eth1. Eth0 is assigned a public IP address where eth1 is assigned a private IP Address for local network. The VM functions as a Firewall/IDS, and the requirement here is to measure the processing time of each appliance.

Is there any way of capturing packets inside the FW and the timestamp of packets IN/OUT?