How to show the datapoint value when mouse hovers to the line chart in visual basic?

If you look at the Github Repo[^], there are samples on how to:
1. Use Tooltips[^]
2. Custom ToolTips[^]

From the UsingTooltips example:

	/// <summary>
	/// This method sets tooltips for chart elements
	/// </summary>
	private void ToolTipChanghed()
	{
		// Set ToolTips for Data Point Series
		Chart1.Series[0].ToolTip = SeriesToolTip.Text;

		// Set ToolTips for legend items
		Chart1.Series[0].LegendToolTip = LegendToolTip.Text;

		// Set ToolTips for the Data Point labels
		Chart1.Series[0].LabelToolTip = PointLabelToolTip.Text;

		// Set ToolTips for second Data Point
		Chart1.Series[0].Points[1].ToolTip = PointToolTip.Text;
	}

	private void UsingToolTips_Load(object sender, System.EventArgs e)
	{
		// Set ToolTips
		ToolTipChanghed();
	}

	private void ToolTip_TextChanged(object sender, System.EventArgs e)
	{
		// Set ToolTips
		ToolTipChanghed();
	}

	private void textBox1_TextChanged(object sender, System.EventArgs e)
	{
		// Set ToolTips
		ToolTipChanghed();
	}
}

You want VB code ... I find ChatGpt is good at converting code, not 100% but enough to get you close. On the odd occasion, it gets it right.

Use: "Convert the following code from C# to VB.net:" and paste the code underneath. You should get the following:

Imports System

Public Class YourClassName
    ''' <summary>
    ''' This method sets tooltips for chart elements
    ''' </summary>
    Private Sub ToolTipChanghed()
        ' Set ToolTips for Data Point Series
        Chart1.Series(0).ToolTip = SeriesToolTip.Text

        ' Set ToolTips for legend items
        Chart1.Series(0).LegendToolTip = LegendToolTip.Text

        ' Set ToolTips for the Data Point labels
        Chart1.Series(0).LabelToolTip = PointLabelToolTip.Text

        ' Set ToolTips for second Data Point
        Chart1.Series(0).Points(1).ToolTip = PointToolTip.Text
    End Sub

    Private Sub UsingToolTips_Load(sender As Object, e As EventArgs)
        ' Set ToolTips
        ToolTipChanghed()
    End Sub

    Private Sub ToolTip_TextChanged(sender As Object, e As EventArgs)
        ' Set ToolTips
        ToolTipChanghed()
    End Sub

    Private Sub textBox1_TextChanged(sender As Object, e As EventArgs)
        ' Set ToolTips
        ToolTipChanghed()
    End Sub
End Class

It looks like the code generated is okay. I have not tested it.

Best thing to do is download the code, compile and run the sample projects. See how it works.

Update

I just downloaded and ran the ChartSamples project and had a poke around. Choose the Index tab, then scroll down to ToolTips, and there you will find 3 examples. All 3 show ToolTips.