List Activities and Connections used in Azure Data Factory Pipelines

SidzOne9 You can use the search box at the top of the Azure Data Factory (ADF) designer to search for the linked service name, and it will show you all of the objects that reference that linked service. 

I also use the Git repo integration in my Dev data factory, and clone that Git repo to my local PC file system. Then you can use the file search tool of your search to find in the contents of file.  My favorite search tool is FileLocator Pro (https://www.mythicsoft.com/). 

You can also use the following PowerShell commands in the Az PowerShell module to retrieve the pipelines (Get-AzDataFactoryPipeline) and datasets (Get-AzDataFactoryDataset) from your ADF resource in Azure, but I think that might be overkill for what you're trying to do. Try searching with the search box and go from there.

PowerShell Az.DataFactory - https://docs.microsoft.com/en-us/powershell/module/Az.DataFactory/?view=azps-3.7.0