\documentclass{article}
\usepackage{graphicx}
\usepackage{xepersian}
\settextfont{Yas}
\setdigitfont{Yas}
\begin{document}
\begin{figure}[!h]
\centerline{\includegraphics[height=2cm]{pic.jpg}}
\caption{\footnotemark[1]}
\end{figure}
 \footnotetext[1]{ Signature}
\end{document}