Use the PowerShell below to get the field schema (Run SharePoint Online Management Shell as administrator):
$SiteURL = "https://domain.sharepoint.com"
Write-Host "Loading CSOM libraries" -foregroundcolor black -backgroundcolor yellow
Add-Type -Path "c:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.dll"
Add-Type -Path "c:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\ISAPI\Microsoft.SharePoint.Client.Runtime.dll"
Write-Host "Lib. successfully loaded !" -foregroundcolor black -backgroundcolor Green
$scriptPath = Split-Path -Parent $MyInvocation.MyCommand.Definition
$User = Read-Host -Prompt "username"
$password = Read-Host -Prompt "Enter password" -AsSecureString
Write-Host "Trying to reach $SiteURL // Handling ClientContext..." -foregroundcolor black -backgroundcolor yellow
$Context = New-Object Microsoft.SharePoint.Client.ClientContext($SiteURL)
$credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($User, $password)
$Context.Credentials = $credentials
$context.RequestTimeOut = 5000 * 60 * 10;
$web = $context.Web
$site = $context.Site
$context.Load($web)
$context.Load($site)
try
{
$context.ExecuteQuery()
Write-Host "Connected !" -foregroundcolor black -backgroundcolor Green
}
catch
{
Write-Host "Impossible to reach $SiteURL : bad password ?" -foregroundcolor black -backgroundcolor Red
return
}
$list = $web.Lists.GetByTitle("Custom List");
$fields = $list.Fields;
$context.Load($web)
$context.Load($site)
$context.Load($list)
$context.Load($fields)
$context.ExecuteQuery()
$fields | select SchemaXML | Export-Csv -path "d:\schema.csv";`
Then follow the article Modified By Column does not get updated check the out of the box Editor field SchemaXML.