IBM's Java JRE is required for the websphere probe as of websphere version 1.5 and higher.
See Help Doc:
Carefully review the prerequisites section in the Help doc.
A Java Virtual Machine (JVM) of the required type and version must be downloaded from IBM?s web site and installed on the computer running the WebSphere probe, and the PATH has to contain the java executable. The version must match the JVM version used to run WAS. You can also copy the Java folder from the WebSphere directory of the Windows WebSphere server to the remote Windows computer in which probe needs to be installed.
Ensure that a version of java.exe exists in the path as described below. This is a prerequisite for dropping the probe, the version of java.exe is at this point not critical.
Later (during the installation wizard launched when double-clicking the probe) you will be asked to select the java.exe version matching the JVM version used to run WAS.
and there are further notes in the Help doc and below...