From cinemablend:
YouTube user Aznmarty256 (via Reddit) took the time to pause when Killmonger is sifting through N'Jobu's journal and transcribe exactly what he wrote to his son. Take a look:
Ungubani? Who are you? I asked this question of myself many times. Often times, I do not know. But I do know I am no longer the man my country knew.
Maybe love? My son?
It has all changed me. T'Chaka must see what we can do, how we can change the course of time for the people who struggle so much in this land. Strangers to me, but my brothers and sisters still. How can I look at them, with the same skin as me, stolen from the same place I came from and not reach out to them? How can I sit idly by and watch in pain and return to Wakanda as if there was nothing to see at all?
Who am I? A war dog who will not leave the lost tribe behind again. Who are you, my son? You will ask this one day and know the answer:
N'Jadaka, son of N'Jobu.
I also tried to take the screenshot of it:
