You can override a dim value <> is default distance. So if we look at this I typed the text twice to see the change.
"\\A1;123.4567 123.45{\\H0.7x;\\S67^;}" so this is mtext you would need to get the dimension value at 4 decimals then build a new string, and put the new string into the dim.
(setq ent (entget (entlast)))
(entmod (subst (cons 1 "123.45{\\H0.7x;\\S67^;}") (assoc 1 ent) ent))
It is best to post a sample dwg with your dim style to use,. The string will need to be made up of 3 parts 123.45 \\H0.7x;\\S 67.
Probably need to use Vla-get-measurement as a entget shows the dim value as ""