As bubblehead mentioned if you have a liquid PH meter do a slurry test and see where that is.
Those soil PH probes do work and I have the $12 and the $75 ones with those probes. The thing is they will vary readings based on the soils moisture content. When dry will reader high when saturated will read lower. My soil profile ranges from 6.8 down to 5.5 and I’m ok with that. I don’t take readings right before watering nor right after watering but a day or so after watering. While I have checked when dry and when saturated in order to learn I have found this to hold true for me.
I find that 3” down it’s higher than it is 6” down and at 9” down will read lower still. The probe I have will measure down to about 11” but most of the cheaper ones only go down “probe lenght” 3-6”.
Post I made about soil meters awhile back.
As far as raising soil PH if needed you can use dolomite lime powder as a top dress and water it in or can mix with water etc. be careful about how much and how fast you increase the PH at one time. There are other products out as well that will raise it too.
Hope this helps