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Code, edit and compile here:
\documentclass{article}\usepackage[T1]{fontenc}\usepackage{textcomp}\usepackage[italian]{babel}\usepackage[a4paper,margin=15mm,bindingoffset=2mm,heightrounded,]{geometry}\usepackage{amsmath}\usepackage{chemfig}\usepackage[version=3]{mhchem}% motivated by section 15.6 of the pgfmanual, @percusses comment https://tex.stackexchange.com/questions/423941/making-the-determination-of-extrema-more-elegant-in-tikz-not-pgfplots#comment1060557_423941% as well as Henri Menkes's answer https://tex.stackexchange.com/a/423952/121799\tikzset{mark path bounding box/.style = {path picture={\coordinate (#1-bl) at (path picture bounding box.south west);\coordinate (#1-tr) at (path picture bounding box.north east);\coordinate (#1-br) at (path picture bounding box.south east);\coordinate (#1-tl) at (path picture bounding box.north west);}}}\begin{document}\schemestart\chemname{\chemfig{@{H1}H-[:30]@{O1}O-[:-30]@{H2}H}}{Stretching simmetrico}\schemestop\chemmove{\path[mark path bounding box=HO](H1)--(O1);\draw[blue,-latex]([yshift=2mm,xshift=-1mm]HO-bl)--([yshift=2mm,xshift=-1mm]HO-tr);\path[mark path bounding box=OH](H2)--(O1);\draw[blue,-latex]([yshift=2mm,xshift=1mm]OH-br)--([yshift=2mm,xshift=1mm]OH-tl);}\hspace{64pt}\schemestart\chemname{\chemfig{@{H1}H-[:30]@{O1}O-[:-30]@{H2}H}}{Stretching asimmetrico}\schemestop\chemmove{\path[mark path bounding box=HO](H1)--(O1);

I add the blue arrow with Inkscape. Is it possible do the same thing with LaTeX? If so, could you tell me how?
Thank you in advance