diff --git a/CHANGES b/CHANGES
index 6076fe86..f7dc626d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5,6 +5,8 @@
 
 * Updated dependency to urllib3>=2 and requests>=2.30.0. See #635
 * Fixed issue when custom adapters were sending only positional args. See #642
+* Expose `unbound_on_send` method in `RequestsMock` class. This method returns new function
+  that is called by `RequestsMock` instead of original `send` method defined by any adapter.
 
 
 0.23.1
diff --git a/responses/__init__.py b/responses/__init__.py
index 4dc64ea1..2666b7c8 100644
--- a/responses/__init__.py
+++ b/responses/__init__.py
@@ -67,12 +67,24 @@
 if TYPE_CHECKING:  # pragma: no cover
     # import only for linter run
     import os
+    from typing import Protocol
     from unittest.mock import _patch as _mock_patcher
 
     from requests import PreparedRequest
     from requests import models
     from urllib3 import Retry as _Retry
 
+    class UnboundSend(Protocol):
+        def __call__(
+            self,
+            adapter: HTTPAdapter,
+            request: PreparedRequest,
+            *args: Any,
+            **kwargs: Any,
+        ) -> models.Response:
+            ...
+
+
 # Block of type annotations
 _Body = Union[str, BaseException, "Response", BufferedReader, bytes, None]
 _F = Callable[..., Any]
@@ -81,6 +93,7 @@
 _HTTPMethodOrResponse = Optional[Union[str, "BaseResponse"]]
 _URLPatternType = Union["Pattern[str]", str]
 
+
 Call = namedtuple("Call", ["request", "response"])
 _real_send = HTTPAdapter.send
 _UNSET = object()
@@ -1089,14 +1102,8 @@ def _on_request(
                 return response
         return response
 
-    def start(self) -> None:
-        if self._patcher:
-            # we must not override value of the _patcher if already applied
-            # this prevents issues when one decorated function is called from
-            # another decorated function
-            return
-
-        def unbound_on_send(
+    def unbound_on_send(self) -> "UnboundSend":
+        def send(
             adapter: "HTTPAdapter",
             request: "PreparedRequest",
             *args: Any,
@@ -1119,7 +1126,16 @@ def unbound_on_send(
 
             return self._on_request(adapter, request, **kwargs)
 
-        self._patcher = std_mock.patch(target=self.target, new=unbound_on_send)
+        return send
+
+    def start(self) -> None:
+        if self._patcher:
+            # we must not override value of the _patcher if already applied
+            # this prevents issues when one decorated function is called from
+            # another decorated function
+            return
+
+        self._patcher = std_mock.patch(target=self.target, new=self.unbound_on_send())
         self._patcher.start()
 
     def stop(self, allow_assert: bool = True) -> None: