\documentclass{article}

\usepackage{venndiagram}
\usepackage{xepersian}
\begin{document}

\begin{figure}[ht]
\centering
\begin{venndiagram3sets}
  \fillNotABC
\end{venndiagram3sets}
\caption{$ \mathcal{U} \setminus (\mathcal{A} \cup \mathcal{B} \cup
\mathcal{C})$}
\end{figure}



%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[ht]
\centering
\begin{venndiagram2sets}
\fillOnlyB
\end{venndiagram2sets}
\caption{$ \mathcal{B} \setminus \mathcal{A} $}
\end{figure}
%%%%%%%%%%%%%%%%%%%%%

\begin{figure}[ht]
\centering
\begin{venndiagram3sets}[labelOnlyA={19},labelOnlyB={2},labelOnlyC={3},
 labelOnlyAB={4},labelOnlyAC={5},labelOnlyBC={6},labelABC={7},
 labelNotABC={8}]
\end{venndiagram3sets}
\end{figure}


%%%%%%%%%%%%%%%%%%%%%

\begin{figure}[ht]
\centering
\begin{venndiagram3sets}[labelOnlyA={1},labelOnlyB={2},labelOnlyC={3},
 labelOnlyAB={4},labelOnlyAC={5},labelOnlyBC={6},labelABC={7},
 labelNotABC={8}]
\setpostvennhook
{
  \draw[<-] (labelA) -- ++(135:3cm) node[above] {\rl{مجموعه اول}};
  \draw[<-] (labelB) -- ++(45:3cm) node[above] {\rl{مجموعه دوم}};
  \draw[<-] (labelC) -- ++(-90:3cm) node[below] {\rl{مجموعه سوم}};
  \draw[<-] (labelABC) -- ++(0:3cm)
    node[right,text width=4cm,align=flush left]{\rl{اشتراک هر سه مجموعه}};
  \draw[<-] (labelNotABC) -- ++(-135:3cm)
    node[below,text width=4cm,align=flush left]{\rl{مجموعه سوم}};
}
\end{venndiagram3sets}
\end{figure}
\end{document}