\version "2.6.0"

\score {
  \relative c'' {
    \time 2/2
    a1 |
    \time 3/2
    \mark \markup { \small { "[" \note #"2" #1.0 "=" \note #"1." #1.0 "]" } }
    a4 g f a g2 |
  }
}