The original manuscript is unclear here. It appears that Oliver Cowdery first started to write either there is or the contracted form there’s (although the latter would have been written without an apostrophe, as theres). Oliver wrote the initial t but then erased it; he continued on by writing heres inline, the contracted form for here’s. Finally, the heres was corrected by erasure and overwriting to here is. This correction is consistent with the fact that the Book of Mormon text completely avoids verbal contractions. Nonetheless, sometimes Oliver initially wrote such contractions in the manuscripts:
There’s also a case in 3 Nephi where the typesetter for the 1837 edition set it is as its (but with no apostrophe):
Surprisingly, this typo was maintained in the LDS textual tradition until 1852.
Elsewhere in the text, we have evidence for both there is and here is as explanatory introductions to a following clause:
Thus the earliest textual sources support both here is and there is. We follow in each case the earliest textual sources, thus the corrected reading here in 𝓞 for Alma 56:9: “but behold here is one thing in which we may have great joy”.
Summary: In Alma 56:9, Oliver Cowdery first started to write in 𝓞 either there is or the contracted form there’s (which he would have spelled as theres, without an apostrophe); he initially corrected this reading to the contracted form here’s (but without the apostrophe); ultimately, he corrected heres to here is, the reading that will be maintained in the critical text.