In my case, I do this:

defmodule Foo do
  require Logger

  defp log_this do
    stacktrace = Process.info(self(), :current_stacktrace) |> elem(1)
    Logger.warn "IMEDIATE CALLER: #{stacktrace |> Enum.at(2) |> Exception.format_stacktrace_entry}"
    Logger.warn "    NEXT CALLER: #{stacktrace |> Enum.at(3) |> Exception.format_stacktrace_entry}"
    "do something"
  end

  def do_something do
    log_this()
    "do something"
  end
  def execute_something do
    do_something()
    "execute_something"
  end
end

iex(1)> Foo.execute_something
10:24:16.528 [warn]  IMEDIATE CALLER: .iex.exs:12: Foo.do_something/0
10:24:16.529 [warn]      NEXT CALLER: .iex.exs:16: Foo.execute_something/0
"execute_something"

You could use :erlang.get_stacktrace/0.