I can compile and install ROS package in the catkin workspace in ROS. How can I export the package in catkin workspace to a .deb file so I can install and use it on the other machines?
My ROS version is ROS Indigo and OS version is Ubuntu 14.04
1 - I think the ROS build farm would be a good starting point and solution for that. You cannot create a .deb as you said but, you can create a source closed ROS packages
The ROS build farm is also designed to enable deploying a custom build farm. This can be useful to release closed-source packages, build for platforms and architectures not provided by the official ROS build farm, and/or customize any part of the process to specific needs.
Take a look here for a better overview.
2 - Another approach would be using a CMake install. Although this will require the same architecture and ROS Distro between both your platforms and a location that can be the same for both machines.
Define a CMAKE_INSTALL_PREFIX for some location like: /opt/your_ros_install.
Run sudo make install to allow installing there.
Copy the install directory from machine A to machine B, using scp or tar or some other technique.
To run your installed ROS packages on either machine: source /opt/your_ros_install/setup.bash.