The only similar name that comes up in any of my materials is Henry Capps b 1822 in TN, d 1901 in MO. I show his wife to be Charlotte Thorp, so I don't think our lines Capps cross directly. If your Johnston County is in NC, then I would look at the NC archives materials online or in a library. They are very extensive and you should be able to find something there.
My Capps line does come from NC, beginning with Thomas Capps -- Jacob Capps, etc., so there is still a chance the two groups are related somewhere.