documentclass[fleqn]{article}
usepackage{amsmath}
usepackage{tikzducks}
begin{document}
This is the standard output:
begin{align}
 vcenter{hbox{tikz[scale=2,remember picture]{%
 duck[graduate=gray!20!black,tassel=red!70!black];
 coordinate (B1) at (1,0.1);
 }}}~=~int!mathrm{d}^4x,
 int!mathrm{d}^4y,int!mathrm{d}^4z,
 frac{1}{(x^2-m^2),(y^2-m^2)}
end{align}
tikz[overlay,remember picture]{draw[gray](B1)--++(9.3cm,0);}
I want to move the equation number up, but not by hand:
begin{align}
 vcenter{hbox{tikz[scale=2,remember picture]{%
 duck[graduate=gray!20!black,tassel=red!70!black];
 coordinate (B2) at (1,0.1);
 }}}~=~int!mathrm{d}^4x,
 int!mathrm{d}^4y,int!mathrm{d}^4z,
 frac{1}{(x^2-m^2),(y^2-m^2)}notag\[-0.6cm] % <-adjusted by hand
end{align}
tikz[overlay,remember picture]{draw[gray](B2)--++(9.3cm,0);}
end{document}