You can pass custom function and a formatter string. Supported options are documented in the Formatter module. Callback is one arity function that receives the generated io list as a param.

defmodule X do
  def y do: :z
end
|> dbg(formatter: "$line: $result", callback: &IO.puts/1)

defmodule Y do
  def x do
    :z
  end
  |> dbg
end