\documentclass{report}
\usepackage{bbm}
\usepackage{xepersian}
\makeatletter
\renewcommand\setdigitfont[2][]{%
  \let\glb@currsize\relax
  \setkeys*[xepersian-mathsdigitspec]{options}{#1}%
  \edef\@tempa{\noexpand\zf@fontspec{Mapping=parsidigits,%
    \XKV@rm}{#2}}\@tempa
  \xepersian@PackageInfo{Defining the default Persian maths digits font as '#2'}
  \DeclareSymbolFont{OPERATORS}   {EU1}{\zf@family} {m}{n}
  \def\persianmathsdigits{%
  \SetMathCode{`0}{\mathalpha}{OPERATORS}{`0}
  \SetMathCode{`1}{\mathalpha}{OPERATORS}{`1}
  \SetMathCode{`2}{\mathalpha}{OPERATORS}{`2}
  \SetMathCode{`3}{\mathalpha}{OPERATORS}{`3}
  \SetMathCode{`4}{\mathalpha}{OPERATORS}{`4}
  \SetMathCode{`5}{\mathalpha}{OPERATORS}{`5}
  \SetMathCode{`6}{\mathalpha}{OPERATORS}{`6}
  \SetMathCode{`7}{\mathalpha}{OPERATORS}{`7}
  \SetMathCode{`8}{\mathalpha}{OPERATORS}{`8}
  \SetMathCode{`9}{\mathalpha}{OPERATORS}{`9}
  \SetMathCode{`\%}{\mathbin}{OPERATORS}{`٪}
  \SetMathCharDef{\decimalseparator}{\mathpunct}{OPERATORS}{"066B}}
}
\makeatother
\settextfont[Scale=1]{Yas}
\setdigitfont[Scale=1]{Yas}
\begin{document}
\[a_1=(b,\mathbbm{1})\]
\end{document}